Russia said it does not plan to use the International Space Station beyond 2020, casting a shadow on U.S. plans to continue cooperation with the country and extend the life of the orbiting laboratory until at least 2024.

Russian Deputy Prime Minister Dmitry Rogozin told reporters Tuesday that Russia is looking to redirect its attention to other projects after 2020. His comments come as tensions mount over U.S. sanctions on Russia for its role in the crisis in Ukraine.

NASA released a statement saying that the U.S. space agency “has not received any official notification from the Government of Russia on any changes in our space cooperation at this point.” NASA added that cooperation in space has been a hallmark of U.S.-Russian relations, even during the Cold War, and it pointed to the past 13 years of continuous human presence on the orbiting outpost.

U.S. State Department spokeswoman Jen Psaki echoed that the United States and Russia have a long history of cooperation in space and that the United States hopes it will continue.

At present, the U.S. space program relies on the Russian program. Ever since NASA retired its aging shuttle fleet in 2011, the only way for astronauts to reach the space station is aboard a Russian Soyuz craft. Private industry has filled a gap by ferrying cargo in low-Earth orbit, and NASA has awarded cargo resupply contracts to the California-based SpaceX and the Virginia-based Orbital Sciences Corporation.

SpaceX did not immediately respond to a request for comment about Rogozin’s statements. Orbital spokesman Barron Beneski told CNN that the company did not have an immediate reaction to the Russian reports, and he noted that the company’s contract calls for the delivery of cargo to the speace station through 2016.

The United States, Russia, Europe, Japan, and Canada are the principal countries involved in the operation of the International Space Station.